The present invention relates to novel urea and urethane monomers. The monomers are useful as strengthening agents for contact lens copolymeric materials, especially hydrogel contact lens materials.
Various monomeric components are known to increase modulus and tear strength when incorporated in copolymeric systems, such as hydrogels used for contact lenses. As an example, compounds such as 2-hydroxy-4-t-butylcyclohexyl methacrylate (TBE) have been disclosed as a strengthening agent in various hydrogel formulations (U.S. Pat. No. 5,006,622). A characteristic feature of such strengthening agents is that they are bulky and are sometimes difficult to synthesize.